// Copyright (c) 2003-2004 Brian Wellington (bwelling@xbill.org)
//
// Copyright (C) 2003-2004 Nominum, Inc.
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
// OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//

package org.xbill.DNS;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
import java.net.InetAddress;
import java.net.UnknownHostException;
import org.xbill.DNS.utils.base16;
import org.xbill.DNS.utils.base32;
import org.xbill.DNS.utils.base64;

/**
 * Tokenizer is used to parse DNS records and zones from text format,
 *
 * @author Brian Wellington
 * @author Bob Halley
 */
public class Tokenizer implements AutoCloseable {

  private static String delim = " \t\n;()\"";
  private static String quotes = "\"";

  /** End of file */
  public static final int EOF = 0;

  /** End of line */
  public static final int EOL = 1;

  /** Whitespace; only returned when wantWhitespace is set */
  public static final int WHITESPACE = 2;

  /** An identifier (unquoted string) */
  public static final int IDENTIFIER = 3;

  /** A quoted string */
  public static final int QUOTED_STRING = 4;

  /** A comment; only returned when wantComment is set */
  public static final int COMMENT = 5;

  private PushbackInputStream is;
  private boolean ungottenToken;
  private int multiline;
  private boolean quoting;
  private String delimiters;
  private Token current;
  private StringBuffer sb;
  private boolean wantClose;

  private String filename;
  private int line;

  public static class Token {
    /** The type of token. */
    public int type;

    /** The value of the token, or null for tokens without values. */
    public String value;

    private Token() {
      type = -1;
      value = null;
    }

    private Token set(int type, StringBuffer value) {
      if (type < 0) {
        throw new IllegalArgumentException();
      }
      this.type = type;
      this.value = value == null ? null : value.toString();
      return this;
    }

    /** Converts the token to a string containing a representation useful for debugging. */
    @Override
    public String toString() {
      switch (type) {
        case EOF:
          return "<eof>";
        case EOL:
          return "<eol>";
        case WHITESPACE:
          return "<whitespace>";
        case IDENTIFIER:
          return "<identifier: " + value + ">";
        case QUOTED_STRING:
          return "<quoted_string: " + value + ">";
        case COMMENT:
          return "<comment: " + value + ">";
        default:
          return "<unknown>";
      }
    }

    /** Indicates whether this token contains a string. */
    public boolean isString() {
      return type == IDENTIFIER || type == QUOTED_STRING;
    }

    /** Indicates whether this token contains an EOL or EOF. */
    public boolean isEOL() {
      return type == EOL || type == EOF;
    }
  }

  /**
   * Creates a Tokenizer from an arbitrary input stream.
   *
   * @param is The InputStream to tokenize.
   */
  public Tokenizer(InputStream is) {
    if (!(is instanceof BufferedInputStream)) {
      is = new BufferedInputStream(is);
    }
    this.is = new PushbackInputStream(is, 2);
    ungottenToken = false;
    multiline = 0;
    quoting = false;
    delimiters = delim;
    current = new Token();
    sb = new StringBuffer();
    filename = "<none>";
    line = 1;
  }

  /**
   * Creates a Tokenizer from a string.
   *
   * @param s The String to tokenize.
   */
  public Tokenizer(String s) {
    this(new ByteArrayInputStream(s.getBytes()));
  }

  /**
   * Creates a Tokenizer from a file.
   *
   * @param f The File to tokenize.
   */
  public Tokenizer(File f) throws FileNotFoundException {
    this(new FileInputStream(f));
    wantClose = true;
    filename = f.getName();
  }

  private int getChar() throws IOException {
    int c = is.read();
    if (c == '\r') {
      int next = is.read();
      if (next != '\n') {
        is.unread(next);
      }
      c = '\n';
    }
    if (c == '\n') {
      line++;
    }
    return c;
  }

  private void ungetChar(int c) throws IOException {
    if (c == -1) {
      return;
    }
    is.unread(c);
    if (c == '\n') {
      line--;
    }
  }

  private int skipWhitespace() throws IOException {
    int skipped = 0;
    while (true) {
      int c = getChar();
      if (c != ' ' && c != '\t') {
        if (!(c == '\n' && multiline > 0)) {
          ungetChar(c);
          return skipped;
        }
      }
      skipped++;
    }
  }

  private void checkUnbalancedParens() throws TextParseException {
    if (multiline > 0) {
      throw exception("unbalanced parentheses");
    }
  }

  /**
   * Gets the next token from a tokenizer.
   *
   * @param wantWhitespace If true, leading whitespace will be returned as a token.
   * @param wantComment If true, comments are returned as tokens.
   * @return The next token in the stream.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public Token get(boolean wantWhitespace, boolean wantComment) throws IOException {
    int type;
    int c;

    if (ungottenToken) {
      ungottenToken = false;
      if (current.type == WHITESPACE) {
        if (wantWhitespace) {
          return current;
        }
      } else if (current.type == COMMENT) {
        if (wantComment) {
          return current;
        }
      } else {
        if (current.type == EOL) {
          line++;
        }
        return current;
      }
    }
    int skipped = skipWhitespace();
    if (skipped > 0 && wantWhitespace) {
      return current.set(WHITESPACE, null);
    }
    type = IDENTIFIER;
    sb.setLength(0);
    while (true) {
      c = getChar();
      if (c == -1 || delimiters.indexOf(c) != -1) {
        if (c == -1) {
          if (quoting) {
            throw exception("EOF in quoted string");
          } else if (sb.length() == 0) {
            return current.set(EOF, null);
          } else {
            return current.set(type, sb);
          }
        }
        if (sb.length() == 0 && type != QUOTED_STRING) {
          if (c == '(') {
            multiline++;
            skipWhitespace();
            continue;
          } else if (c == ')') {
            if (multiline <= 0) {
              throw exception("invalid close parenthesis");
            }
            multiline--;
            skipWhitespace();
            continue;
          } else if (c == '"') {
            if (!quoting) {
              quoting = true;
              delimiters = quotes;
              type = QUOTED_STRING;
            } else {
              quoting = false;
              delimiters = delim;
              skipWhitespace();
            }
            continue;
          } else if (c == '\n') {
            return current.set(EOL, null);
          } else if (c == ';') {
            while (true) {
              c = getChar();
              if (c == '\n' || c == -1) {
                break;
              }
              sb.append((char) c);
            }
            if (wantComment) {
              ungetChar(c);
              return current.set(COMMENT, sb);
            } else if (c == -1 && type != QUOTED_STRING) {
              checkUnbalancedParens();
              return current.set(EOF, null);
            } else if (multiline > 0) {
              skipWhitespace();
              sb.setLength(0);
              continue;
            } else {
              return current.set(EOL, null);
            }
          } else {
            throw new IllegalStateException();
          }
        } else {
          ungetChar(c);
        }
        break;
      } else if (c == '\\') {
        c = getChar();
        if (c == -1) {
          throw exception("unterminated escape sequence");
        }
        sb.append('\\');
      } else if (quoting && c == '\n') {
        throw exception("newline in quoted string");
      }
      sb.append((char) c);
    }
    if (sb.length() == 0 && type != QUOTED_STRING) {
      checkUnbalancedParens();
      return current.set(EOF, null);
    }
    return current.set(type, sb);
  }

  /**
   * Gets the next token from a tokenizer, ignoring whitespace and comments.
   *
   * @return The next token in the stream.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public Token get() throws IOException {
    return get(false, false);
  }

  /**
   * Returns a token to the stream, so that it will be returned by the next call to get().
   *
   * @throws IllegalStateException There are already ungotten tokens.
   */
  public void unget() {
    if (ungottenToken) {
      throw new IllegalStateException("Cannot unget multiple tokens");
    }
    if (current.type == EOL) {
      line--;
    }
    ungottenToken = true;
  }

  /**
   * Gets the next token from a tokenizer and converts it to a string.
   *
   * @return The next token in the stream, as a string.
   * @throws TextParseException The input was invalid or not a string.
   * @throws IOException An I/O error occurred.
   */
  public String getString() throws IOException {
    Token next = get();
    if (!next.isString()) {
      throw exception("expected a string");
    }
    return next.value;
  }

  private String _getIdentifier(String expected) throws IOException {
    Token next = get();
    if (next.type != IDENTIFIER) {
      throw exception("expected " + expected);
    }
    return next.value;
  }

  /**
   * Gets the next token from a tokenizer, ensures it is an unquoted string, and converts it to a
   * string.
   *
   * @return The next token in the stream, as a string.
   * @throws TextParseException The input was invalid or not an unquoted string.
   * @throws IOException An I/O error occurred.
   */
  public String getIdentifier() throws IOException {
    return _getIdentifier("an identifier");
  }

  /**
   * Gets the next token from a tokenizer and converts it to a long.
   *
   * @return The next token in the stream, as a long.
   * @throws TextParseException The input was invalid or not a long.
   * @throws IOException An I/O error occurred.
   */
  public long getLong() throws IOException {
    String next = _getIdentifier("an integer");
    if (!Character.isDigit(next.charAt(0))) {
      throw exception("expected an integer");
    }
    try {
      return Long.parseLong(next);
    } catch (NumberFormatException e) {
      throw exception("expected an integer");
    }
  }

  /**
   * Gets the next token from a tokenizer and converts it to an unsigned 32 bit integer.
   *
   * @return The next token in the stream, as an unsigned 32 bit integer.
   * @throws TextParseException The input was invalid or not an unsigned 32 bit integer.
   * @throws IOException An I/O error occurred.
   */
  public long getUInt32() throws IOException {
    long l = getLong();
    if (l < 0 || l > 0xFFFFFFFFL) {
      throw exception("expected an 32 bit unsigned integer");
    }
    return l;
  }

  /**
   * Gets the next token from a tokenizer and converts it to an unsigned 16 bit integer.
   *
   * @return The next token in the stream, as an unsigned 16 bit integer.
   * @throws TextParseException The input was invalid or not an unsigned 16 bit integer.
   * @throws IOException An I/O error occurred.
   */
  public int getUInt16() throws IOException {
    long l = getLong();
    if (l < 0 || l > 0xFFFFL) {
      throw exception("expected an 16 bit unsigned integer");
    }
    return (int) l;
  }

  /**
   * Gets the next token from a tokenizer and converts it to an unsigned 8 bit integer.
   *
   * @return The next token in the stream, as an unsigned 8 bit integer.
   * @throws TextParseException The input was invalid or not an unsigned 8 bit integer.
   * @throws IOException An I/O error occurred.
   */
  public int getUInt8() throws IOException {
    long l = getLong();
    if (l < 0 || l > 0xFFL) {
      throw exception("expected an 8 bit unsigned integer");
    }
    return (int) l;
  }

  /**
   * Gets the next token from a tokenizer and parses it as a TTL.
   *
   * @return The next token in the stream, as an unsigned 32 bit integer.
   * @throws TextParseException The input was not valid.
   * @throws IOException An I/O error occurred.
   * @see TTL
   */
  public long getTTL() throws IOException {
    String next = _getIdentifier("a TTL value");
    try {
      return TTL.parseTTL(next);
    } catch (NumberFormatException e) {
      throw exception("expected a TTL value");
    }
  }

  /**
   * Gets the next token from a tokenizer and parses it as if it were a TTL.
   *
   * @return The next token in the stream, as an unsigned 32 bit integer.
   * @throws TextParseException The input was not valid.
   * @throws IOException An I/O error occurred.
   * @see TTL
   */
  public long getTTLLike() throws IOException {
    String next = _getIdentifier("a TTL-like value");
    try {
      return TTL.parse(next, false);
    } catch (NumberFormatException e) {
      throw exception("expected a TTL-like value");
    }
  }

  /**
   * Gets the next token from a tokenizer and converts it to a name.
   *
   * @param origin The origin to append to relative names.
   * @return The next token in the stream, as a name.
   * @throws TextParseException The input was invalid or not a valid name.
   * @throws IOException An I/O error occurred.
   * @throws RelativeNameException The parsed name was relative, even with the origin.
   * @see Name
   */
  public Name getName(Name origin) throws IOException {
    String next = _getIdentifier("a name");
    try {
      Name name = Name.fromString(next, origin);
      if (!name.isAbsolute()) {
        throw new RelativeNameException(name);
      }
      return name;
    } catch (TextParseException e) {
      throw exception(e.getMessage());
    }
  }

  /**
   * Gets the next token from a tokenizer and converts it to a byte array containing an IP address.
   *
   * @param family The address family.
   * @return The next token in the stream, as an byte array representing an IP address.
   * @throws TextParseException The input was invalid or not a valid address.
   * @throws IOException An I/O error occurred.
   * @see Address
   */
  public byte[] getAddressBytes(int family) throws IOException {
    String next = _getIdentifier("an address");
    byte[] bytes = Address.toByteArray(next, family);
    if (bytes == null) {
      throw exception("Invalid address: " + next);
    }
    return bytes;
  }

  /**
   * Gets the next token from a tokenizer and converts it to an IP Address.
   *
   * @param family The address family.
   * @return The next token in the stream, as an InetAddress
   * @throws TextParseException The input was invalid or not a valid address.
   * @throws IOException An I/O error occurred.
   * @see Address
   */
  public InetAddress getAddress(int family) throws IOException {
    String next = _getIdentifier("an address");
    try {
      return Address.getByAddress(next, family);
    } catch (UnknownHostException e) {
      throw exception(e.getMessage());
    }
  }

  /**
   * Gets the next token from a tokenizer, which must be an EOL or EOF.
   *
   * @throws TextParseException The input was invalid or not an EOL or EOF token.
   * @throws IOException An I/O error occurred.
   */
  public void getEOL() throws IOException {
    Token next = get();
    if (next.type != EOL && next.type != EOF) {
      throw exception("expected EOL or EOF");
    }
  }

  /** Returns a concatenation of the remaining strings from a Tokenizer. */
  private String remainingStrings() throws IOException {
    StringBuffer buffer = null;
    while (true) {
      Tokenizer.Token t = get();
      if (!t.isString()) {
        break;
      }
      if (buffer == null) {
        buffer = new StringBuffer();
      }
      buffer.append(t.value);
    }
    unget();
    if (buffer == null) {
      return null;
    }
    return buffer.toString();
  }

  /**
   * Gets the remaining string tokens until an EOL/EOF is seen, concatenates them together, and
   * converts the base64 encoded data to a byte array.
   *
   * @param required If true, an exception will be thrown if no strings remain; otherwise null be be
   *     returned.
   * @return The byte array containing the decoded strings, or null if there were no strings to
   *     decode.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getBase64(boolean required) throws IOException {
    String s = remainingStrings();
    if (s == null) {
      if (required) {
        throw exception("expected base64 encoded string");
      } else {
        return null;
      }
    }
    byte[] array = base64.fromString(s);
    if (array == null) {
      throw exception("invalid base64 encoding");
    }
    return array;
  }

  /**
   * Gets the remaining string tokens until an EOL/EOF is seen, concatenates them together, and
   * converts the base64 encoded data to a byte array.
   *
   * @return The byte array containing the decoded strings, or null if there were no strings to
   *     decode.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getBase64() throws IOException {
    return getBase64(false);
  }

  /**
   * Gets the remaining string tokens until an EOL/EOF is seen, concatenates them together, and
   * converts the hex encoded data to a byte array.
   *
   * @param required If true, an exception will be thrown if no strings remain; otherwise null be be
   *     returned.
   * @return The byte array containing the decoded strings, or null if there were no strings to
   *     decode.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getHex(boolean required) throws IOException {
    String s = remainingStrings();
    if (s == null) {
      if (required) {
        throw exception("expected hex encoded string");
      } else {
        return null;
      }
    }
    byte[] array = base16.fromString(s);
    if (array == null) {
      throw exception("invalid hex encoding");
    }
    return array;
  }

  /**
   * Gets the remaining string tokens until an EOL/EOF is seen, concatenates them together, and
   * converts the hex encoded data to a byte array.
   *
   * @return The byte array containing the decoded strings, or null if there were no strings to
   *     decode.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getHex() throws IOException {
    return getHex(false);
  }

  /**
   * Gets the next token from a tokenizer and decodes it as hex.
   *
   * @return The byte array containing the decoded string.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getHexString() throws IOException {
    String next = _getIdentifier("a hex string");
    byte[] array = base16.fromString(next);
    if (array == null) {
      throw exception("invalid hex encoding");
    }
    return array;
  }

  /**
   * Gets the next token from a tokenizer and decodes it as base32.
   *
   * @param b32 The base32 context to decode with.
   * @return The byte array containing the decoded string.
   * @throws TextParseException The input was invalid.
   * @throws IOException An I/O error occurred.
   */
  public byte[] getBase32String(base32 b32) throws IOException {
    String next = _getIdentifier("a base32 string");
    byte[] array = b32.fromString(next);
    if (array == null) {
      throw exception("invalid base32 encoding");
    }
    return array;
  }

  /**
   * Creates an exception which includes the current state in the error message
   *
   * @param s The error message to include.
   * @return The exception to be thrown
   */
  public TextParseException exception(String s) {
    return new TextParseException(filename + ":" + line + ": " + s);
  }

  /** Closes any files opened by this tokenizer. */
  @Override
  public void close() {
    if (wantClose) {
      try {
        is.close();
      } catch (IOException e) {
      }
    }
  }
}
